@startuml
'https://plantuml.com/sequence-diagram

Actor User
Boundary GUI

User --> GUI : User selects crop
GUI --> User : Dialogue box pops up asking for co-ordinates
User --> GUI : User specifies co-ordinates
GUI --> CropImage : manipulateImage()
CropImage --> GUI : New image is created and sent back to the GUI
GUI --> User : User sees new image

@enduml